Fan-casing



A. W. CARLSON.

FAN CASING.

APPucATloN FILED JAN.31.1919.

1,370,283. Patented Mar. 1, 19211.

ZM/5&7

UNITED STATES PATENT OFFICE.

AXEL W. CARLSON, OF WORCESTER, MASSACHUSETTS, ASSIGNOR TO CARLING TUR- BINE BLOWER CO., 0F WORCESTER, MASSACHUSETTS, A CORPORATION OF MASSA- OHUSETTS.

FAN-CASING.

Specication of Letters Patent.

Patented Mar. 1, 1921.

Original application filed May 27, 1918, Serial No. 236,810. Divided and this application filed January 31, 1919. Serial No. 274,295.

To all vwhom t may concern.'

Be it known that 1, AXEL TW. CARLSON, a citizen of the Ynited States, residing at vorcester, in the county of YVorcester and State of Massachusetts, have invented a new and useful Fan-Casing, of which the following is a specification.

This invention relates to a casing through which air may be drawn and. discharged by a rotary fan, this specification forming a division of m prior application, Serial No. 236,810, sied iiiay 27, 191s.

ltis the general objectof my invention to improve the design and construction of such fan casings to the end that a quieter and more eiiicient operation may be obtained.

1With this general object in view, my invention relates particularly to the provision of an improved fan casing or air tube which comprises a substantially cylindrical intermediate portion adjacent the fan blades combined with an enlarged or bell-shaped entrance portion and a conical discharge portion, preferably of small outward taper.

Further features of my invention relate to arrangements and combinations of parts hereinafter described and more particularly pointed out in the appended claims.

A preferred form of my invention is shown in the drawing in which Figure 1 is a vertical sectional view of my improved casing, and Figs. 2 and 3 are partial sectional piewstaken along the lines 2 2 and 3-3 in Referring to the drawing, I have shown a fan 10 having blades 11 and mounted on a shaft 12 supported by a bearing 13. My invention resides in the fan casing 14 surrounding the fan l0 and suitably supported, as by a frame 15. This casing comprises an enlarged or bell-shaped entrance portion 16 which preferably extends to a point substantially midway between the sides of the fan blades 11. At this point the portion 16 merges with a short substantially cylindrical portion 1T, extending approximately to the outer edge of the blades 11, where it joins a conical discharge portion 18, preferably of relatively small outward taper. The ends of the fan blades are closely adjacent the easing.

lthas been found in practice that this partlcular form of fan casing possesses important advantages in use, and that a fan surrounded by a casing of this type operates with increased efficiency and reduced noise, both of which results are extremely desirable. T he bell shaped entrance permits the air to move easily and quietly along natural How lines in approaching the fan. The short cylindrical portion prevents leakage around the tip of the blade and enables the fan to exert efficient pressure on the air, and the gradual expansion in the conical discharge portion reduces back pressure, while substantially preventing the formation of eddy currents. T his is particularly important when the air is discharged from the fan casing into an air duct or passage, as the air in applicants fan casing will be moving substantially along the axis of such duct or passage, when it enters the same from applicants conical discharge portion.

Having thus described my invention, it will be evidentthat changes and modifications can be made therein bythose skilled in the art without departing from the spirit and scope'thereof, as set forth in the claims and I do not wish to be otherwise limited to the details herein disclosed, but what l claim is- 1. In a blower having a fan, a fan casing surrounding said fan, said fan casing having an enlarged entrance portion, a substantially cylindrical intermediate portion closely adjacent the blades of said fan, and a conical discharge port-ion with a relatively small outward taper.

2. In a blower having a fan, a fan easin surrounding said fan and having a bellshaped entrance portion extending to a point substantially midway of the width of the fan blades and merging with a substantially cylindrical intermediate portion for the remaining width of said blades, said casing AXEL W. CARLSON. 

